Evaluation of antioxidant potentials of some fruits and other plant organs widely consumed in Turkey

Oxidative stress is an inevitable consequence for aerobic organisms. Itgenerates the production of reactive oxygen species which may causedetrimental effects to biological systems. It is known for playing a crucial role inthe etiology of several diseases including diabetes, cancer and cardiovasculardisorders. To increase the body?s antioxidant potential for fighting againstoxidative stress, it has been recommended that individuals increase their intakeof dietary antioxidants. Regular consumption of fruits and vegetables containingnatural antioxidants is associated with reducing the risk of various diseases.Hence, we chose three edible fruits consumed widely in Turkey: Cornus mas L.,Diospyros kaki L. and Laurocerasus officinalis Roem. to evaluate theirantioxidant capacity both in vitro and in vivo. We also studied the antioxidanteffects of the leaves of C. mas under increased oxidative stress conditions,since they are traditionally used against diabetes, and oxidative stress is clearlyattributed to diabetes. In vitro screening tests indicated that 80% methanolicextracts of all studied plants have high antioxidant activity in terms of freeradical scavenging and metal reducing activity. In vivo antioxidant studies onhealthy rats demonstrated that the antioxidant capacity of liver homogenateswere increased, although no changes were observed in the activities ofantioxidant enzymes SOD, CAT and GSH-Px or in the level of lipid peroxidation.Studies on CCl4?induced oxidative damage also showed that 80% methanolicextract of C. mas leaves restored the activities of antioxidant enzymes, loweredthe level of lipid peroxidation and elevated the total antioxidant capacities ofboth total blood and liver homogenates of the animals. Further activity guidedfractionation studies led to the isolation of gallic acid, a well known antioxidant.